This invention relates to a method used for retarding the staling of bread and other baked products and extending their shelf life.
Baked products, such as bread, muffins, cakes, cookies, donuts and other pastries, typically are subject to staling and other instabilities. For example, after manufacture, such products tend to lose their desirable texture and flavor qualities associated with freshness.
In particular, enriched breads, such as the familiar mass-produced, slice wrapped white breads have relatively short shelf lives, and can have shelf-lives of about five days or less, after which it typically is considered to be stale. So-called xe2x80x9csweet bakedxe2x80x9d products that have high sugar and fat content (such as donuts and cake) tend to stale at a slower rate because the presence of sugar and fat retard staling, but products with lower sugar and fat content (such as muffins) stale relatively quickly.
The product and monetary losses for the international baked products industry due to such staling are substantial. The relatively short shelf-life of bread products and sweet baked products with lower sugar and fat content also has resulted in a need to create and maintain production and distribution systems that operate within the limited window of salability proscribed by the staling phenomenaxe2x80x94resulting in further production, warehousing, inventory control and distribution inefficiencies.
Various techniques and additives to increase the length of time before staling (and thus the shelf life) of baked products, in particular bread products, have been developed and used. These have included the use of use of preservatives in the dough mix, reduction of oxygen content of packaging, reduction of moisture loss and acidification. These approaches have also included use of controlled atmospheric packaging and incorporation in the bread dough of additives which inhibit enzymatic and non-enzymatic browning.
It was demonstrated by Boussingault in 1852 that the staling of bread is not due to the loss of moisture by the drying-out process. In his experiments, Boussingault sealed bread in a glass tube to prevent moisture loss. He found that although the moisture content remained constant under these conditions, the bread became stale. As breads lose moisture during storage, however, they become firmer and less acceptable. It is generally known that breads containing higher levels of water stale at a slower rate. J. B. Boussingault. Experiments to determine the transformation of fresh bread into stale bread. Ann. Chem. Phys. 36:490, 1852. Hence, improved packaging can lead to reduced staling, but packaging cannot eliminate staling. Further, some baked products (including breads and muffins) can be and are sold without packaging.
Kim and. D""Appolonia have shown that addition of water insoluble pentosans to bread doughs slow down the overall aging of starch gels and hence retard bread staling. Pentosans of flour have similar properties to vegetable gums. They are viscous at room temperature, thin out during heating, and are highly hydrophilic. Although effective in retarding bread staling, water insoluble pentosans have resulted in remarkable reduction in bread volume. Bread volume is considered one of the most important, if not the single most important attribute of a bread product, so materially reducing volume reduces the quality of the bread. S. K. Kim and B. J. D""Appolonia. Effect of pentosans on the retardation of wheat starch gels. Cereal Chemistry: 54:150, 1977.
Bacterial amylases derived from B. Subtilis, and other maltogenic amylases may be added to bread doughs as anti-staling agents. The enzymes work on the starch fraction of flour modifying the starch components in such a way that retrogradation is less likely to occur; they create low molecular weight sugars and dextrins which improve the water retention capacity of the baked goods. The difficulty in applying most enzymes commercially is that the activity must be carefully controlled for a wide variety of conditions encountered during bread baking and in distribution. At levels even 0.1% above recommended levels, or at higher storage temperatures all than expected, the enzyme activity in bread is so high that the bread becomes gummy and sticky and unacceptable to the consumer. Also, excessive amounts of the amylases and low baking temperatures produce gummy and weak crumb structure, causing problems at the slicer. At carefully controlled levels, however, amylases have been shown to retard bread firmness. M. Maleki, A. Schulz, and J. M. Bruaemmer. Staling of bread. II Effect of bacterial, fungal and cereal alpha-amylases on freshness. Getreide Mehl Brot. 26:211, 1972. Enzymes, however, are difficult to integrate and uniformly mix into a baked product; the amount of enzymes added have to be carefully calibrated. If enzymes are added at too high a level; the entire batch can be ruined.
The baking industry uses surface-active lipids, emulsifiers and crumb softeners, to produce the soft type bread preferred by most consumers. It is debatable as to whether surfactants actually decrease the rate of firming or merely produce soft bread whose crumb then firms at the same rate as that of bread made without surfactants. Pelshenki and Hampel have confirmed that shortening and emulsifiers resulted in softer bread crumb only during the first six hours after baking. Thereafter, both crumb firming and starch retrogradation increased more rapidly as compared with crumb containing no fat or surface active lipids. P. E. Pelshenki and G. Hampel. Baker""s Digest. 36(3):48, 1962.
Therefore, despite extensive research of bread and other baked products staling during the past century, bakery products are still perishable. In particular, bread products stale relatively quickly. The majority of researchers attribute firmness changes principally to the physiochemical reactions of the amylopectin fraction of the starch components; although flour proteins may be involved to some degree. Retarding the firming rate (staling) by technological means such as processing, formulation, storage conditions, and additives has been of limited benefit. The main softening effects have been produced by the use of lipid surfactants. The use of heat-stable xcex1-amylase and other enzymes is difficult to control but may be potentially useful. The known techniques have resulted in limited extensions of shelf life for commercial baked products, but these techniques sometimes result in negative organoleptic effects on the final baked products. Hence, there remains a need for developing techniques that decrease the rate of staling in baked products (particularly bread) without adversely affecting the handling properties of the dough (an important factor in commercial baking contexts where mass quantities of dough is processed) or the organoleptic qualities of the final product.
It has been discovered that polydextrose, when added to dough mixes, can retard staling in baked products, including bread. It has also been discovered that polydextrose may, in some contexts, improve certain dough handling properties and may also increase bread volume.
Polydextrose is a randomly bonded condensation polymer of D-glucose with some bound sorbitol and a suitable acid (e.g. citric acid). It is odorless and has a slight, tart taste. Polydextrose is very soluble in water. It is known to have uses as a fat substitute, foodstuff bulking agent, browning agent, texturizer, humectant and thickener for use in, for example, reduced-calorie products. Such reduced-calorie products include fat-free cookies, low-fat frozen desserts, reduced-fat peanut butter and fat-free salad dressings. It is believed that polydextrose does not contribute to dental cavities, does not cause as significant gastrointestinal disturbances, and does not significantly have caloric potential. Polydextrose typically can be melted at temperatures exceeding above 130 degrees Celsius. A typical 10 percent solution with water has a pH of approximately 2.5 to 3.5. The United States Food and Drug administration has approved polydextrose as a multipurpose food ingredient for such products as frozen dairy desserts, baked goods and mixes, confections and frostings, salad dressings, gelatins, puddings, and pie fillings, hard candy and soft candy, and chewing gum. Polydextrose has also been approved by various other nations"" regulatory bodies for use as a food ingredient.
LITESSE(copyright) improved polydextrose FCC is a commercially available form of polydextrose available from Cultor Food Science which produces other forms of polydextrose.
Polydextrose has a higher water absorption capacity and thus increases the content of soluble carbohydrates. It is thought that the primary effect of polydextrose in reducing the rate of staling in baked products is to dilute the starch components thus reducing the available starch fractions for crystallization.
Emulsifiers such as glycerol monostearate are improved complexing agents with amylase and amylopectin fractions of starch. Maltogenic xcex1-amylases are less sensitive to storage temperature fluctuations. A combination of polydextrose, emulsifiers and maltogenic xcex1-amylases in a dough mix produces a baked product with a soft crumb texture and with a slower rate of staling. In addition, it has been discovered that a combination of polydextrose and fibre in a dough mix can result in a synergistic effect, improving dough handling properties and slowing down the rate of staling in the baked product.
The present invention alleviates to a great extent the disadvantages of the known anti-staling agents by providing a method for using polydextrose as an ingredient in baked products. The use of polydextrose in combination with flour, alone or in combination with certain emulsifiers and enzymes in accordance with the present invention provides improved anti-staling properties, improvement in bread crumb structure for breads and other baked products. These improved- properties are generally achieved without adverse affect upon organoleptic characteristics of the baked goods. The dough made with the present invention demonstrates good handling properties and the final baked product is equal in quality or better than control breads baked without polydextrose. Moreover, gumminess that is normally associated with the use of enzymatic anti-staling compositions is also eliminated or minimized by the dosages of enzyme used according to the invention.
For breads and other non-sweetened baked goods, polydextrose is preferably added in the amount of between 1 percent to about 5 percent by flour weight, with polydextrose added in an amount of between about 2 percent to about 3 percent being particularly preferred. In sweet baked goods (such as muffins, cakes, pie crusts and the like) polydextrose is preferably added in the amount of between about 4% to about 10% by flour weight, with polydextrose added in an amount of between 4% to about 6% being particularly preferred. Too much polydextrose results in a sticky dough which cannot be processed efficiently.
The present invention can be used with commonly used dough preparation processes, such as the straight dough process, the sour dough process, the Chorleywood bread process and the sponge and dough process. The method of the present invention can be used to manufacture bread as well as sweet baked products such as cakes, muffins and pies.
In one embodiment, polydextrose is used in combination with emulsifier. Optionally, such an emulsifier can include glyceryl monostearate, mono-diglycerides, sodium stearyl lactylate and Datem (diacetyl tartaric esters of mono- and diglycerides). In another embodiment, polydextrose is used in combination with an enzyme or in combination with an enzyme and an emulsifier. Suitable enzymes could include bacterial and fungal amylases, pullulanase, amyloglucosidase, pentosanase, xylanase, and maltogenic xcex1-amylase.
In yet another embodiment, polydextrose is used in combination with fiber. The combination of polydextrose and fiber shows some synergistic results, and produces a less sticky dough, and improved dough firmness and crumb cohesiveness.